reset: allow reset on unborn branch

Some users seem to think, knowingly or not, that being on an unborn
branch is like having a commit with an empty tree checked out, but
when run on an unborn branch, "git reset" currently fails with:

  fatal: Failed to resolve 'HEAD' as a valid ref.

Instead of making users figure out that they should run

 git rm --cached -r .

, let's teach "git reset" without a revision argument, when on an
unborn branch, to behave as if the user asked to reset to an empty
tree. Don't take the analogy with an empty commit too far, though, but
still disallow explictly referring to HEAD in "git reset HEAD".

Signed-off-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/t/t7106-reset-unborn-branch.sh b/t/t7106-reset-unborn-branch.sh
new file mode 100755
index 0000000..8062cf5
--- /dev/null
+++ b/t/t7106-reset-unborn-branch.sh
@@ -0,0 +1,52 @@
+#!/bin/sh
+
+test_description='git reset should work on unborn branch'
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	echo a >a &&
+	echo b >b
+'
+
+test_expect_success 'reset' '
+	git add a b &&
+	git reset &&
+	test "$(git ls-files)" = ""
+'
+
+test_expect_success 'reset HEAD' '
+	rm .git/index &&
+	git add a b &&
+	test_must_fail git reset HEAD
+'
+
+test_expect_success 'reset $file' '
+	rm .git/index &&
+	git add a b &&
+	git reset a &&
+	test "$(git ls-files)" = "b"
+'
+
+test_expect_success 'reset -p' '
+	rm .git/index &&
+	git add a &&
+	echo y | git reset -p &&
+	test "$(git ls-files)" = ""
+'
+
+test_expect_success 'reset --soft is a no-op' '
+	rm .git/index &&
+	git add a &&
+	git reset --soft
+	test "$(git ls-files)" = "a"
+'
+
+test_expect_success 'reset --hard' '
+	rm .git/index &&
+	git add a &&
+	git reset --hard &&
+	test "$(git ls-files)" = "" &&
+	test_path_is_missing a
+'
+
+test_done